Add font size argument in text Wireframe builder

[louiszawadzki]

What and why?

Add font size argument in createTextWireframe public builder.

Today passing a font argument is the only way to specify a font size for the text wireframe.
With React Native text views we don't get direct access to the UIFont. However we get direct access to the fontSize,
so we can bypass this by creating a new font on every call, but that takes a lot of time and impacts performance (on an app I tested, it took up to 300ms of time over a minute of usage of the app).

I've tried passing nil as font (DataDog/dd-sdk-reactnative#570), but then all elements have a small font size.

I believe enabling to specify only the font size is the best way to get a great fidelity with a small performance cost.

How?

It seems that there is no test covering this part of the code, let me know if I should add some.

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference
• Add CHANGELOG entry for user facing changes

Custom CI job configuration (optional)

• Run unit tests for Core, RUM, Trace, Logs, CR and WVT
• Run unit tests for Session Replay
• Run integration tests
• Run smoke tests
• Run tests for tools/

[maciejburda]

I don't entirely like the fact that it's now implicitly either fontSize or font.size. Maybe we could rename to fontSizeOverride ?

[maciejburda]

One non-blocking suggestion

[datadog-datadog-prod-us1]

Datadog Report

Branch report: louiszawadzki/add-font-size-in-text-wireframe
Commit report: bea5879
Test service: dd-sdk-ios

✅ 0 Failed, 256 Passed, 0 Skipped, 4m 35.27s Wall Time